【作者】 李好斌；

【导师】 温长顺；

【作者基本信息】 中国地质大学（北京） ， 构造地质学， 2007， 博士

【摘要】 通过野外地质研究,大滩-四子王旗-召河庙近东西向构造岩浆岩带由色尔腾山岩群和太古代变形变质的花岗质岩侵入体组成,构造带的总体几何学特征是片理走向近东西。据构造带地质体分布及剪切变形特征自北而南划分为:北带、中带和南带,均具有右行运动特征。南带面理北倾,倾角30~45°,b线理走向基本与剪切面理走向一致,倾角一般小于20°,具右行逆冲的运动学特征;中带变形相对较弱,面理近直立;北带剪切面理主要南倾,局部北倾,倾角50~80°,b线理走向一致于面理,倾角小于30°,拉伸线理倾向近于面理倾向,倾角一般大于60°,具有右行斜落的运动学特点。岩石学研究表明色尔腾山岩群形成于岛弧环境,花岗质侵入岩则是同构造期侵位的同熔型花岗岩,具有壳幔混染特点,色尔腾山岩群与侵入体共同构成了华北北缘花岗岩绿岩带,主要经历了绿片岩-角闪岩相的变形变质作用。其主要的构造变形可分为两期褶皱作用和晚期的韧性剪切变形,变形变质过程是构造带隆起的过程,也是华北陆块北缘陆块固结增生的过程,奠定了华北陆块北缘早前寒武纪构造格架的基础。显微构造研究表明,其变形矿物主要是长石、石英及云母类矿物,长石有钾长石和斜长石,一般形成碎斑,呈眼球状或透镜状产出,其长轴方向平行于糜棱面理,多发生旋转而形成具指向意义的“σ”型碎斑系,长石透镜体和石英颗粒呈书斜式排列的“多米诺骨牌式”结构;可见长石双晶的弯曲现象及长石斑晶变形形成共轭-同向微裂隙构造。石英的碎斑、集合体、同构造眼球体、矩形石英条带构造,波状消光、长轴定向分布形成S面理,与剪切面理构成S-C组构;云母类矿物构成“云母鱼”形态,局部钾长石出现蠕英结构等显微构造组合类型等,这种显微构造组合特征相当于Scholz模式中的绿片岩带,即地壳深度11~22km,T=300~450℃。更多还原

【Abstract】 Field geological study shows that the nearly east-to-west tectonic magma belt of Datan—Siziwangqi—Zhaohe-Temple is composed of the Seerteng Moutain rock-group and the granitic intrusions metamorphosed in the Archeozoic Era. The general geometric feature is schistosity strike nearly east-west. According to the plastid distribution of the tectonic belt and the shear deformation, this tectonic magma belt can be divided as follows: the north zone, the middle zone and the south zone, each of which is characterized by dextral movement. In the south zone, the plane tilts to the north, with an angle of 30—45°. Its lineation strike is approximately identical with that of shear plane, with its dip angle less than 200, and it has the kinematic feature of dextral thrusting. In the middle zone there exists relatively weak deformation and the plane is nearly vertical. The shear plane in the north zone tilts mainly to the south and some parts to the north, with dip angle 50-80°.。Its lineation strike is identical with that of plane,with dip angle less than 300. The inclination of stretching lineation is approximate to that of plane,and the dip angle is more than 600.,with the kinematic characteristics of dextral and oblique falling.Lithologic study shows that the rock group of Seerteng Mountain was formed in island arc, while the granitic intrusive rocks are the syntactic granites intruded in the syntectonic phase, with the crust-mantle contamination characteristics. Seerteng Group and the intrusions together constitute the granite greenstone belt on the northern margin of North China, which mainly experienced greenschist—amphibolite~facies metamorphic role. Its major tectonic deformation can be divided into folding action of two periods and the late ductile shear deformation. In the metamorphic process, the tectonic belt became up-gravity and the landmasses on the northern margin of North China became concreted and proliferated. It lays the foundation for the early Precambrian structural framework of the landmasses on the northern margin of North China.Microstructural study shows that the deformed minerals are mainly feldspar, quartz and mica. There are two types of feldspar: K-feldspar and plagioclase. These minerals are generally formed in the shape of tiny augen-porphyroblast or lense. The direction of its long lexis is parallel to that of mylonitic plane and the tiny porphyroblast group which shows the shape of“σ”and has the function of orientation are formed after rotation. Feldspar lens and quartz particles have a“domino-style”structure. Therefore, the bending of feldspar twin and the deformation of feldspar porphyritic crystals leads to the formation of conjugate----the same directional micro-cracks. Based on the porphyroblasts of feldspar, aggregates, synkinematic augen , rectangular quartz stripped structure, wavy extinction and the long axis orientation distribution, S-plane is formed and it is grouped with shear plane structure S-C. Mica minerals constitute a picture of“mica fish”. Part of the K-feldspar presents myrmekitic quartz texture, and this microstructural feature is equivalent to greenschist of Scholz model with that depth of crust being 11-22km T=300-4500C.更多还原